The Addiator was a mechanical add/subtract calculator

Calculator

An electronic calculator is a small, portable, usually inexpensive electronic device used to perform the basic operations of arithmetic. Modern calculators are more portable than most computers, though most PDAs are comparable in size to handheld calculators.The first solid-state electronic...

, made by Addiator Gesellschaft, Berlin

Berlin

Berlin is the capital city of Germany and is one of the 16 states of Germany. With a population of 3.45 million people, Berlin is Germany's largest city. It is the second most populous city proper and the seventh most populous urban area in the European Union...

. Variants of it were sold from 1920 until 1982. It was composed of sheet-metal sliders inside a metal envelope, manipulated by a stylus, with an innovative carry mechanism, doing subtract ten, carry one with a simple stylus movement.

Only made obsolete by the electronic variety, it was simple and cheap. It also handled non-decimal measurements, like feet and inches, or pre-decimalization pounds, shillings, and pence

Pound sterling

The pound sterling , commonly called the pound, is the official currency of the United Kingdom, its Crown Dependencies and the British Overseas Territories of South Georgia and the South Sandwich Islands, British Antarctic Territory and Tristan da Cunha. It is subdivided into 100 pence...

. Addition and subtraction required different 'screens', handled by turning the instrument over, or flipping a front panel, or, later, by extended sliders and an extra lower panel.

More expensive versions had a built-in slide rule

Slide rule

The slide rule, also known colloquially as a slipstick, is a mechanical analog computer. The slide rule is used primarily for multiplication and division, and also for functions such as roots, logarithms and trigonometry, but is not normally used for addition or subtraction.Slide rules come in a...

on the back.

This type of calculator was introduced by the Frenchman Troncet in 1889. The Addiator was one of the most popular calculators of this sort, and the name is often used to refer to the type generally.

External links

• http://www.vintagecalculators.com/html/addiator.html
• http://www.addiator.de Addiator museum
• http://www.calculators.de calculator museum
• http://www.peterkernwein.de/Rechengeraete-Sammlung/addiator_universal.htm Addiators and many other calculators
• http://www.uni-greifswald.de/~wwwmathe/RTS/rh200414.html Another beautiful picture
• http://www.tcocd.de/index.shtml Collection of calculating devices
• http://www.rechnerlexikon.de/en/artikel/Addiator
• Addiator photos and manuals hosted at www.computercollector.com
• Addiator photos